The importance of strain selection on the viability and survival of probiotic bacteria in dairy foods.

摘要

Probiotic starter cultures were subjected to viability tests including exposure to low pH, high bile concentration, high sucrose concentration, high oxygen content and low storage temperature. The survival of the probiotic bacteria in these tests was strain dependant. After 3 h of exposure to pH 2 media, Bifidobacterium infantis 1912 decreased from 1.2 X 1011 to 1.1 X 1010 cfu/ml and Lactobacillus acidophilus 2401 decreased from 2.2 X 1011 to 4.9 X 109 cfu/ml. After 3 h of exposure to 2% bile solution, B. infantis 1912 decreased from 5.2 X 107 to 9.7 X 106 cfu/ml and L. acidophilus 2401 decreased from 5.3 X 103 to 2.9 X 106 cfu/ml. In 25% sucrose, B. infantis 1912 decreased from 2.4 X 108 to 8.9 X 107 cfu/ml over 3 h and L. acidophilus 2401 decreased from 1.1 X 1011 to 6.0 X 109 cfu/ml. During 3 h refrigeration, B. infantis 1912 decreased from 5.2 X 107 to 2.6 X 107 cfu/ml and L. acidophilus 2401 decreased from 5.2 X 106 to 2.0 X 105 cfu/ml. During 3 h frozen storage, B. infantis 1912 decreased from 5.2 X 107 to 3.0 X 107 cfu/ml and L. acidophilus 2401 decreased from 5.2 X 106 to 9.0 X 105 cfu/ml. The results for the oxygen sensitivity test varied strain by strain. The results showed that probiotic strain selection is an important prerequisite for incorporation into cultured milk products to achieve enhanced viability and survival.